Dell released BIOS updates for its two flagship laptops over the last couple days. The specific devices that have updates available are the XPS 13 (9350) and the XPS 15 (9550). They're the latest models, with Intel's sixth generation Skylake processors.
Here's what's new:
Dell XPS 13
Version 1.4.4, last updated 7/4/16
- Improve touchscreen disable feature functionality
- Added Support for Pre-OS MAC Address pass-through support for Dell Docks and specific Dell LAN Dongles. Display of MAC Address pass-through value in BIOS Setup.
- Improved Type-C device performance and stability
Dell XPS 15
Version 1.02.10, last updated 7/5/16
- Fixed Dell Thunderbolt Dock (TB15) device will lost after S3 resume
- Fixed LCD flickering when in lowest brightness
- Fixed After McAfee encrypted, the PCIE NVMe SSD \ SATA SSD can't boot to OS issue
- Fixed Wake on WLAN takes a long time with Intel 1830/1820A Wireless card
- Fixed USB audio/mouse may be lag while connected to Dell Thunderbolt Dock (TB15) and Dell Dock (WD15)
- Support for Windows 10 Enterprise features
- Fixed incorrect Thunderbolt security level reading from Driver
- Fixed Touchpad may be lost after Dell Thunderbolt Dock (TB15) device connected
- Add passthrough MAC address shows on BIOS Setup feature.
- Fixed System will become shut-down with connected to Dell Thunderbolt Dock (TB15) after S4 Resume.
While both devices have a range of improvements, it's clear that the XPS 15 is much more significant. It's probably an update that you'll want to install.
Both laptops sit at the top of their respective classes. In fact, the Dell XPS 15 sits as a direct - albeit significantly less expensive - competitor to the 15" MacBook Pro. Both are in a rare class of quad-core laptops that aren't considered to be gaming PCs.